The short answer
Most unknown numbers can be identified for free in a minute: listen to the voicemail, check the label your phone shows, and search the full number online. If none of that turns up a person or a business, the call was most likely a robocall or a scam, and the number on your screen may not even belong to the caller.
Check a number against scam reports
Type the number below. We check it against the complaints people filed with the FTC in the last 30 days and against the scam numbers PhoneShield’s front desk refuses. It is free, and we don’t save the numbers you check.
Free ways to find out who called you
- Listen to the voicemail. Real callers usually leave one. A recording that hangs up, a few seconds of silence or a message that tells you to press a key is almost always a robocall.
- Look at the name and the label on your phone. Your carrier looks up a caller ID name for many landlines and business numbers. Cell numbers often show only a city and state, because most cell phones have no name on file. A label such as Scam Likely, Spam Risk or Potential Spam means your carrier or phone judged the call. Our Scam Likely guide explains who shows what.
- Search the full number in a search engine, in quotes and with the area code. Businesses, clinics and schools usually list their numbers, and numbers that call thousands of people tend to show up on complaint pages.
- Check your carrier’s app. T-Mobile’s Scam Shield includes a reverse number lookup, and the other carriers’ call-protection apps show their own caller ID and spam information.
- Check the reports. The FTC publishes the phone numbers people report in Do Not Call and robocall complaints every weekday. It is raw data rather than a lookup page, and the FTC doesn’t verify it, but call-blocking apps and some lookup sites draw on it. If the call was a scam, add your own report at ReportFraud.ftc.gov.
Reverse phone lookup sites: what you actually get
A reverse phone lookup site takes a number and gives back a name, an address and sometimes much more. The FTC counts these people search sites as data brokers: they build their reports from public records, social media and data bought from other brokers.
- The free part is thin. Most show the city and the phone company for free and ask for a payment or a subscription for the name, often after a long “searching” animation. Read the price and how to cancel before you pay.
- Cell numbers are the weak spot. They change hands, and the records behind them can be years old. A name you pay for may belong to the number’s last owner.
- Your own number is in there too. The same sites sell reports about you. The FTC explains how to opt out site by site, for free.
A lookup site helps most with a landline or a small business that called once. It helps least with the calls people most want to identify: repeated robocalls, which rarely come from a number registered to the caller.
Caller ID apps: Hiya, Truecaller and RoboKiller
Caller ID apps name the caller while the phone rings, from their own databases. They work in different ways:
| App | How it knows who is calling | Worth knowing |
|---|---|---|
| Hiya | A reputation for each number, from call patterns and reports | Also built into some phones and carrier apps |
| Truecaller | A directory of names, built partly from its users’ uploaded contacts | Your number may be listed by someone else’s phone; you can unlist it at truecaller.com/unlisting |
| RoboKiller | Its spam list plus analysis of the call’s audio | Answers suspected spam with recordings that waste the caller’s time |
All of them do best with businesses and with numbers many people have already reported. A scammer calling from a number that is new today, or from a borrowed one, often shows up as an ordinary unknown caller. Our comparison of spam call blocker apps covers prices and trade-offs.
When the number isn't really theirs
Scammers fake the number your phone shows. The FCC calls it spoofing. A common version, neighbor spoofing, shows a number that looks local, often with your own area code. Another shows the real number of a bank or a government office.
A lookup of a spoofed number points at whoever really owns it: a stranger, a business, sometimes a number that isn’t in service. That is why a search that turns up an ordinary family or a pharmacy doesn’t clear the call. If the caller asked for money, a code or personal details, treat it as a scam whatever the lookup says. If people call you saying your number called them, your number is probably being spoofed; scammers usually move on to another number within hours.
Why you shouldn't call an unknown number back
- It tells the dialer your line works. Answered and returned calls are what keep a number on scammers’ lists.
- Some numbers charge you. In the one-ring scam, the phone rings once and stops so you call back. The number looks like a US area code but is an international toll line, such as 809 for the Dominican Republic, and the charges show up on your bill. The FCC suggests asking your phone company to block outgoing international calls if you never make them.
- A borrowed number reaches the wrong person. With spoofing, the person who answers your call back never called you.
If the voicemail says it is your bank, Medicare, the IRS or a relative in trouble, hang up and call the number you already know: the one on the back of your card, on an official website or in your own contacts.
When the same caller won’t stop
Repeated calls from a person, rather than a robocaller, are a different problem. Block the number from your recent calls, and keep a simple log: the date, the time, the number shown and anything the caller said. Save voicemails and texts. Then call your phone company, which can trace calls and change your number, and the police if the calls threaten you. The police can ask the phone company for records you can’t get yourself.
How to stop unknown calls
If what you really want is fewer of these calls, three settings do most of the work:
- iPhone: Settings, Apps, Phone, Screen Unknown Callers. Ask Reason for Calling has the iPhone ask unknown callers who they are before it rings; Silence sends them to voicemail. Step by step in how to block spam calls on iPhone.
- Android: the Phone app’s spam filter, and on Pixel phones Call Screen. See how to block spam calls on Android.
- Your carrier: T-Mobile Scam Block, AT&T ActiveArmor and Verizon Call Filter are free. The full list is in how to stop and block spam calls.
Silencing every unknown number also silences the new doctor’s office and the pharmacy, so check voicemail often if you choose it.
Knowing who called before you pick up
Looking a number up after the call is guesswork. PhoneShield asks the caller instead. Calls to a protected number reach a front desk first: numbers on PhoneShield’s shared scam list and numbers with repeated FTC complaints are refused before the phone rings, and everyone else who isn’t a contact is asked who they are and why they are calling.
A real caller gives a name and a reason and rings through or leaves a message, depending on how the line is set up. The family sees every call in the app with what the caller said, so “who called me?” has an answer before anyone picks up. No screening catches every scam, but it takes the guesswork out of unknown numbers. PhoneShield is $29.99 a month for one line. See how a call is handled.
Questions people ask
How can I find out who called me from an unknown number?
Start with what is free: listen to the voicemail, look at the name and any spam label your phone shows, and search the full number in a search engine. Businesses, doctors' offices and known scam numbers usually turn up. If nothing does, the caller most likely was a robocaller or a scammer using a borrowed or made-up number.
Is there a free reverse phone lookup?
A search engine is the best free one. Your phone's own spam label and your carrier's tools are free too; T-Mobile's Scam Shield, for one, includes a reverse number lookup. Most reverse phone lookup websites show a city and carrier for free and charge for a name, especially for cell numbers.
Are reverse phone lookup sites accurate?
Often not for cell phones. They are people search sites, a kind of data broker, and they piece reports together from public records and purchased data, which can be years old. A scam call with a faked caller ID also points the lookup at an innocent person whose number was borrowed.
Should I call back a number I don't recognize?
No. A call back tells the caller the line works, and some numbers that look American are international toll numbers that charge you per minute. This is the one-ring scam. If the caller said they were your bank, a doctor or a government office, call the number you already have for them instead.
Can a caller ID app tell me who called?
Sometimes. Apps like Hiya, Truecaller and RoboKiller name callers from their own databases and flag numbers many people have reported. They do best with businesses and known spam numbers. Truecaller's directory is built partly from its users' contact lists, so read what you agree to share before you install it.
Can you find out who called from a blocked or private number?
Usually not. Your phone company has the number but won't show it to you. Paid unmasking services exist, and on many landlines *57 starts a trace that goes to the phone company and the police. Our No Caller ID guide covers the details.
How can I stop unknown phone calls?
On iPhone, turn on Screen Unknown Callers in Settings, Apps, Phone; on Android, turn on the spam filter in the Phone app. Add your carrier's free blocking on top. To stop unknown callers without missing the ones you want, have a service answer them first and ask who is calling.